Add --include-line-numbers flag (#6)

2 files changed, 44 insertions, 15 deletions

diff --git a/spark-common/src/main/java/me/lucko/spark/sampler/node/AbstractNode.java b/spark-common/src/main/java/me/lucko/spark/sampler/node/AbstractNode.java
index e660140..75632c4 100644
--- a/spark-common/src/main/java/me/lucko/spark/sampler/node/AbstractNode.java
+++ b/spark-common/src/main/java/me/lucko/spark/sampler/node/AbstractNode.java
@@ -53,30 +53,47 @@ public abstract class AbstractNode {
         return this.totalTime.longValue();
     }
 
-    private AbstractNode resolveChild(String className, String methodName) {
+    private AbstractNode resolveChild(String className, String methodName, int lineNumber) {
         return this.children.computeIfAbsent(
-                StackTraceNode.generateKey(className, methodName),
-                name -> new StackTraceNode(className, methodName)
+                StackTraceNode.generateKey(className, methodName, lineNumber),
+                name -> new StackTraceNode(className, methodName, lineNumber)
         );
     }
 
-    public void log(StackTraceElement[] elements, long time) {
-        log(elements, 0, time);
+    public void log(StackTraceElement[] elements, long time, boolean includeLineNumbers) {
+        log(elements, 0, time, includeLineNumbers);
     }
     
-    private void log(StackTraceElement[] elements, int skip, long time) {
+    private void log(StackTraceElement[] elements, int offset, long time, boolean includeLineNumbers) {
         this.totalTime.add(time);
 
-        if (skip >= MAX_STACK_DEPTH) {
+        if (offset >= MAX_STACK_DEPTH) {
             return;
         }
         
-        if (elements.length - skip == 0) {
+        if (elements.length - offset == 0) {
             return;
         }
-        
-        StackTraceElement bottom = elements[elements.length - (skip + 1)];
-        resolveChild(bottom.getClassName(), bottom.getMethodName()).log(elements, skip + 1, time);
+
+        // the first element in the array is the top of the call stack, and the last is the root
+        // offset starts at 0.
+
+        // pointer is determined by subtracting the offset from the index of the last element
+        int pointer = (elements.length - 1) - offset;
+        StackTraceElement element = elements[pointer];
+
+        // the parent stack element is located at pointer+1.
+        // when the current offset is 0, we know the current pointer is at the last element in the
+        // array (the root) and therefore there is no parent.
+        StackTraceElement parent = offset == 0 ? null : elements[pointer + 1];
+
+        // get the line number of the parent element - the line which called "us"
+        int lineNumber = parent == null || !includeLineNumbers ? StackTraceNode.NULL_LINE_NUMBER : parent.getLineNumber();
+
+        // resolve a child element within the structure for the element at pointer
+        AbstractNode child = resolveChild(element.getClassName(), element.getMethodName(), lineNumber);
+        // call the log method on the found child, with an incremented offset.
+        child.log(elements, offset + 1, time, includeLineNumbers);
     }
 
     private Collection<? extends AbstractNode> getChildren() {
diff --git a/spark-common/src/main/java/me/lucko/spark/sampler/node/StackTraceNode.java b/spark-common/src/main/java/me/lucko/spark/sampler/node/StackTraceNode.java
index d161b42..ee9e985 100644
--- a/spark-common/src/main/java/me/lucko/spark/sampler/node/StackTraceNode.java
+++ b/spark-common/src/main/java/me/lucko/spark/sampler/node/StackTraceNode.java
@@ -31,34 +31,46 @@ import java.io.IOException;
 public final class StackTraceNode extends AbstractNode implements Comparable<StackTraceNode> {
 
     /**
+     * Magic number to denote "no present" line number for a node.
+     */
+    public static final int NULL_LINE_NUMBER = -1;
+
+    /**
      * Forms a key to represent the given node.
      *
      * @param className the name of the class
      * @param methodName the name of the method
+     * @param lineNumber the line number of the parent method call
      * @return the key
      */
-    static String generateKey(String className, String methodName) {
-        return className + "." + methodName;
+    static String generateKey(String className, String methodName, int lineNumber) {
+        return className + "." + methodName + "." + lineNumber;
     }
 
     /** The name of the class */
     private final String className;
     /** The name of the method */
     private final String methodName;
+    /** The line number of the invocation which created this node */
+    private final int lineNumber;
 
-    public StackTraceNode(String className, String methodName) {
+    public StackTraceNode(String className, String methodName, int lineNumber) {
         this.className = className;
         this.methodName = methodName;
+        this.lineNumber = lineNumber;
     }
 
     @Override
     protected void appendMetadata(JsonWriter writer) throws IOException {
         writer.name("cl").value(this.className);
         writer.name("m").value(this.methodName);
+        if (this.lineNumber != NULL_LINE_NUMBER) {
+            writer.name("ln").value(this.lineNumber);
+        }
     }
 
     private String key() {
-        return generateKey(this.className, this.methodName);
+        return generateKey(this.className, this.methodName, this.lineNumber);
     }
 
     @Override